Switchable Hi-Z input impedance, how ?

[tinitus]

man, I forgot it would need two controls per tone control curcuit

its beginning to look a bit tight
and forgot I also need a mute switch
if bypass switch has 3 positions, mute could be in the middle
but a toggle switch might be easier and faster to use
opinions ?

[tinitus]

bypass switch
I think it will take the signal directly to the solid state output, through a hi-z input jfet buffer

this way it will also be functional without tubes

and I will need a way to bypass any effect devices connected to input side

man, I hate it, but might have to put the power switch on the backplate, to get more room on the front

[tinitus]

ahh, regarding switches and bypass functions, there seems to be a few basic terms one needs know

single pole single throw = SPST
single pole double throw = SPDT
and so on
or if much more variations, there could be numbers instead
might be handy when looking at switches specsheets
and to know exactly which model to buy/order

for the bypass function we may need look only at SPDT, DPDT, 3PDT

[tinitus]

cleaned out schematic a bit, and getting closer I hope

[shanx]

A mute position on the middle of bypass (channel?) selector switch would seem to be the proper place for it

[tinitus]

Originally Posted by shanx

.... selector switch would seem to be the proper place for it

most likely, yes

Im working on it
with regards to attenuation pots, the tone controls seem to be a bit of a problem
but I could ofcourse just fill it up with buffers

thinking about using only one tube instead of two
but easy to change

[shanx]

Hi Tinitus,
If you are having problems with tone stack, maybe you should download Tonestack Calculator from Duncan Amps. It is free and very useful for setting up different resistance and capacitance. There are a lot of styles too, fender type vox, marshall. You could ''tune'' the response curves for bass. Are you getting too much signal attenuation on your tone controls?

[tinitus]

Originally Posted by shanx

Are you getting too much signal attenuation on your tone controls?

looks like I mostly need cut/attenuation

but might be too early to say yet
having seperat biamped midrange and bass channel may change things
should give me more control
at least that was one reason of doing it
if Im very lucky I wont need anything else

[tinitus]

Originally Posted by tinitus

looks like I mostly need cut/attenuation

hey, for a first try, with tube curcuit only, I could try the trick with a 'too small' bypass cap on the cathod resistor
maybe something like 1uf
or selectable cap size/options, by a simple switch

[tinitus]

while waiting for power supply parts, hunting 6n1p curcuits

but why are there not two curcuits using same resistor values, or at least just the same anode voltage
but no, all different

could it come from 'adoption' of ecc88/6DJ8 curcuits
but 6n1p is not exactly the same
and 'ev' types maybe even more different